1. Field of the Invention
This invention relates to a printer for recording information on a recording medium using a light beam such as a laser beam modulated by a signal representing the information to be recorded, and more particularly to a light beam rotary printer for recording information using a light beam emitted from a light source mounted on a rotator.
2. Description of the Prior Art
Lasers can emit light beams having a high spatial coherence and high spectral line brightness difficult to obtain with other light sources and therefore are used in many optical recording devices and reading devices. As optical recording devices using such laser beams, there have been known those which employ a galvanometer mirror or a rotating multifaceted mirror to deflect a laser beam modulated by a signal representing information to be recorded to two-dimensionally scan a recording medium. However, those recording devices are disadvantageous in that the manufacturing cost thereof is high since expensive elements such as a rotating mirror and an f.theta. lens are required, and that the recording cannot be effected with a high resolution and a high brightness since the laser beam cannot be highly concentrated due to the long optical path, between the condenser lens system in the laser beam projecting system and the recording medium, which is inherent to the recording device of the above structure. There has been proposed a printer employing a drum type platen which is rotated with a recording medium placed on the peripheral surface thereof, and a laser beam projecting system disposed near the platen in order to reduce the optical distance between the condenser lens system and the recording medium. In such a recording device, the main scanning is effected by rotating the platen and the sub scanning is effected by reciprocating the laser beam projecting system. However, this device is disadvantageous in that the platen must be large in order to support a recording medium of a practical size and is difficult to rotate a large platen at a high speed to obtain a high recording speed.